Switching Scheme for Opting In and Out of Multi-User Orthogonal Frequency-Division Multiple Access

ABSTRACT

This document describes methods, devices, systems, and means for a switching scheme for opting in and out of multi-user orthogonal frequency-division multiple access (MU-OFDMA). In one aspect, an electronic device enters the MU-OFDMA mode to communicate via a wireless network over a shared-channel bandwidth. During the MU-OFDMA mode, the electronic device determines that an uplink-queue size is greater than a first threshold size. Responsive to the determining, the electronic device opts out of the MU-OFDMA mode and enters a single-user mode to contend for a transmit channel for transmitting uplink data.

BACKGROUND

The Wi-Fi Alliance (WFA) has developed a new standard called 802.11ax,which boosts Wi-Fi performance by implementing several schemes includingmulti-user orthogonal frequency-division multiple access (MU-OFDMA). InMU-OFDMA, channel bandwidth is shared among multiple users in bothuplink and downlink transmissions. To achieve a target high efficiency,an 802.11ax access point aims to maximize the time used by devices inMU-OFDMA over the time used by the devices in a single-user (SU) mode.This target high efficiency is achieved by the access point forcing thedevices to be less competitive in the medium contention window and waitfor triggers sent by the access point by using a more-relaxed set ofEnhanced Multimedia Distributed Control Access (EDCA) parametersrelative to those used by the access point.

For example, the access point sends to an 11ax device (e.g., a deviceconfigured for 802.11ax), a MU-EDCA Parameter Set information element inmanagement frames including beacon, probe response, associate response,and re-associate response. This information element includes a new setof values of EDCA (e.g., Arbitration Inter-Frame Spacing Number (AIFSN),Exponent form of Minimum Contention Window (ECWmin), and Exponent formof Maximum Contention Window (ECWmax)) for each access category. Thosevalues are more relaxed than the initial set passed in the EDCAParameter Set element. The MU-EDCA Parameter Set information elementalso includes a timer value for how long these parameters take effect(e.g., MU-EDCA Timer).

The 11ax device participating in MU-OFDMA would have to wait fortriggers from the access point and abide by a scheduling algorithm inthe access point for transmitting uplink traffic (e.g., uplink data andcontrol signals). However, a legacy device would contend moreaggressively to obtain the channel and would get full access to thebandwidth of the channel for its transmission. This makes the 11axdevice participating in MU-OFDMA more inferior to legacy devices inhigh-traffic load scenarios.

SUMMARY

This summary is provided to introduce simplified concepts of a switchingscheme for opting in and out of multi-user orthogonal frequency-divisionmultiple access (MU-OFDMA). In one example, an electronic device can optout of an MU-OFDMA mode (“multi-user mode”) when uplink traffic is high(e.g., above a threshold), which allows the electronic device to enter asingle-user mode to maximize throughput by transmitting its uplink datawithout sharing channel bandwidth with other devices and without accessrestrictions mandated by the access point. In another example, theelectronic device can opt out of the MU-OFDMA mode if low-latencyrequirements are critical, such as for an online gaming application, andif the access point is not responsive enough to meet those requirements.In yet another example, the electronic device can opt out of theMU-OFDMA mode based on Basic Service Set (BSS) metrics, such as if theelectronic device estimates, based on a signal-strength measurement of atransmit channel, that the transmit channel can handle more data thanthe access point is allowing the electronic device to transmit under themulti-user mode. Opting out of the multi-user mode enables theelectronic device to enter the single-user mode and contend for thetransmit channel without any restrictions mandated by the access point.

The simplified concepts are further described below in the DetailedDescription. This summary is not intended to identify essential featuresof the claimed subject matter nor is it intended for use in determiningthe scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of one or more aspects of a switching scheme for opting inand out of MU-OFDMA are described below. The use of the same referencenumbers in different instances in the description and the figuresindicate similar elements:

FIG. 1 illustrates an example environment, which includes one or moreelectronic devices and a Wi-Fi access point.

FIG. 2 illustrates an example device diagram of an access point and anelectronic device in more detail.

FIG. 3 depicts an example method for opting in and out of MU-OFDMA whenuplink traffic is high.

FIG. 4 depicts an example method for opting out of MU-OFDMA to honorlow-latency Quality-of-Service (QoS) requirements.

FIG. 5 depicts an example method for opting out of MU-OFDMA based onBasic Service Set (BSS) metrics.

DETAILED DESCRIPTION Overview

This document describes methods, devices, systems, and means for aswitching scheme for opting in and out of multi-user orthogonalfrequency-division multiple access (MU-OFDMA). Conventional techniquesused to achieve high efficiency and utilization of MU-OFDMA cause 11axelectronic devices (e.g., devices configured for 802.11ax) participatingin MU-OFDMA to be inferior to legacy devices in heavy-traffic loadscenarios because the 11ax devices are forced to be less competitive inthe medium contention window and wait for triggers sent by the accesspoint(s). Techniques are described to balance between preserving highefficiency in low-traffic (non-critical latency) scenarios for overallBasic Service Set (BSS) efficiency and being as aggressive in contentionwhen data load or latency requirements are critical. Thus, thetechniques described herein are directed to a switching scheme foropting in and out of MU-OFDMA.

In one aspect, a method for opting in or out of an MU-OFDMA mode isdisclosed. The method includes an electronic device entering theMU-OFDMA mode to communicate via a wireless network over ashared-channel bandwidth. In addition, the method includes, during theMU-OFDMA mode, determining that an uplink-queue size is greater than afirst threshold size. The method also includes, responsive to thedetermining, opting out of the MU-OFDMA mode and entering a single-usermode to contend for a transmit channel for transmitting uplink data.

In another aspect, an electronic device is disclosed. The electronicdevice includes a memory and processor system configured to executeinstructions stored in the memory to implement an access-mode managerapplication configured to manage transmission and reception of signalsover a wireless network according to an MU-OFDMA mode. The access-modemanager application is also configured to enter a low-latency mode fortransmission of uplink data for an application. In addition, theaccess-mode manager application is configured to, during the MU-OFDMAmode and the low-latency mode of the electronic device, monitor afrequency at which triggers are received from an access point on thewireless network to determine whether to continue using the MU-OFDMAmode or to opt out of the MU-OFDMA mode.

In another aspect, a method for opting out of an MU-OFDMA mode isdisclosed. The method is performed by an electronic device and includes,when connected to a wireless network using the MU-OFDMA mode, indicatingto an access point of the wireless network that the electronic devicehas uplink data to transmit. The method also includes receiving one ormore triggers from the access point for transmitting the uplink data,the one or more triggers including a mandated modulation and codingscheme (MCS). In addition, the method includes performing a clearchannel assessment (CCA) of a transmit channel, measuring a signalstrength of the transmit channel, estimating an MCS based on themeasured signal strength, and comparing a first data rate associatedwith the estimated MCS to a second data rate associated with themandated MCS to determine whether to opt out of the MU-OFDMA mode.

Example Environment

FIG. 1 illustrates an example environment 100, which includes one ormore electronic devices 110 and a Wi-Fi access point 120. Each of thesedevices may be wireless-network-enabled and capable of communicatingdata, packets, and/or frames over a wireless link 130. The wireless link130 may include any suitable type of wireless communication link orwireless network connection. For example, the wireless link 130 may beimplemented in whole or in part as a wireless local-area-network (WLAN),ad-hoc WLAN (e.g., a direct wireless link), wireless mesh network,near-field communication (NFC) link, wireless personal-area-network(WPAN), wireless wide-area-network (WWAN), or short-range wirelessnetwork. The wireless link 130 may be implemented in accordance with anysuitable communication protocol or Institute of Electrical andElectronics Engineers (IEEE) standard, such as IEEE 802.11-2012, IEEE802.11-2016, IEEE 802.11ac, IEEE 802.11ad, IEEE 802.11ab, IEEE 802.11ax,and the like. By using IEEE 802.11ax, the electronic device 110 canoperate in radio bands between, and including, 1 and 6 GHz, such as 2.4GHz, 5 GHz, and 6 GHz radio bands.

In this example, the access point 120 is implemented to provide andmanage a wireless network that includes the wireless link 130. Thewireless links 130 may be implemented with any suitable modulation andcoding scheme (MCS), such as orthogonal frequency division multiplexingaccess (OFDMA). In other cases, the access point 120 may include or beembodied as a host device, enhanced node base station, wireless router,broadband router, modem device, drone controller, vehicle-based networkdevice, or other network administration node or device. Using IEEE802.11ax, the access point 120 may provide multiple Wi-Fi networks, a2.4 GHz Wi-Fi network (“AP2G”), a 5 GHz Wi-Fi network (“AP5G”), and/or a6 GHz Wi-Fi network (“AP6G”). The electronic device 110 may detect bothWi-Fi networks using a multi-user (MU) OFDMA mode. The electronic devicemay also have Multiple Input Multiple Output (MIMO) capabilities.

The electronic device(s) 110 operate as stations in the wireless networkprovided by the access point 120. The electronic device 110 may includea smart-phone, set-top box, tablet computer, a wireless speaker, awireless smart-speaker, a camera, a wearable device, a wireless printer,a mobile station, a laptop computer, a medical device, a securitysystem, a drone, an Internet-of-Things (IoT) device, a gaming device, asmart appliance, an Internet-protocol enabled television (IP TV), apersonal media device, a navigation device, a mobile-internet device(MID), a network-attached-storage (NAS) drive, a mobile gaming console,and so on.

Generally, the access point 120 provides connectivity to the Internet,other networks, or network-resources through a backhaul link (notshown), which may be either wired or wireless (e.g., a T1 line, fiberoptic link, broadband cable network, intranet, a wireless-wide-areanetwork). The backhaul link may include or connect with data networksoperated by an internet service provider, such as a digital subscriberline or broadband cable provider, and may interface with the accesspoint 120 via an appropriately configured modem (not shown). Whileassociated with the wireless network provided by the access point 120(e.g., via the wireless links 130), the electronic device(s) 110 mayaccess the Internet, exchange data with each other, or access othernetworks for which the access point 120 acts as a gateway.

Example Devices

FIG. 2 illustrates an example device diagram 200 of an access point andan electronic device in more detail. In aspects, the device diagram 200describes devices that can implement various aspects of a switchingscheme for opting in and out of MU-OFDMA. The electronic device(s) 110operates as a station (STA) in the wireless network provided by theaccess point 120. As a station, the electronic device 110 includes oneor more antennas 202 and one or more transceivers 204 for communicatingwith the access point 120 or other wirelessly-enabled devices. Thetransceivers 204 may include any suitable number of respectivecommunication paths (e.g., transmit or receive chains) to supporttransmission or reception of multiple spatial streams of data. Front-endcircuitry (not shown) of the electronic device(s) 110 may couple orconnect the transceiver 204 to the antennas 202 to facilitate varioustypes of wireless communication. The antennas 202 may include an arrayof multiple antennas that are configured similar to or differently fromeach other.

The electronic device(s) 110 also includes processor(s) 206 and memory208 (computer-readable storage media 208, CRM 208). The processor(s) 206may be a single core processor or a multiple core processor composed ofa variety of materials, such as silicon, polysilicon, high-K dielectric,copper, and so on. The computer-readable storage media described hereinexcludes propagating signals. CRM 208 may include any suitable memory orstorage device such as random-access memory (RAM), static RAM (SRAM),dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), orFlash memory useable to store device data 210 of the electronicdevice(s) 110. The device data 210 includes user data, multimedia data,applications, and/or an operating system of the electronic device(s) 110that are executable by processor(s) 206 to enable wireless communicationand user interaction with the electronic device(s) 110. In the contextof the disclosure, the CRM 208 is implemented as storage media, and thusdoes not include transitory signals or carrier waves.

CRM 208 also includes an access-mode manager 212 (e.g., access-modemanager application 212). Alternately or additionally, the access-modemanager 212 may be implemented in whole or part as hardware logic orcircuitry integrated with or separate from other components of theelectronic device(s) 110. In at least some aspects, the access-modemanager 212 configures the transceiver(s) 204 to implement thetechniques described herein for a switching scheme for opting in and outof MU-OFDMA.

The access point 120 includes one or more antennas 252 and one or moretransceivers 254 for communicating with the electronic device(s) 110 orother wirelessly-enabled devices. The transceivers 254 may include anysuitable number of respective communication paths (e.g., transmit orreceive chains) to support transmission or reception of multiple spatialstreams of data. Front-end circuitry (not shown) of the access point 120may couple or connect the transceiver 254 to the antennas 252 tofacilitate various types of wireless communication. The antennas 252 mayinclude an array of multiple antennas that are configured similar to ordifferent from each other.

The access point 120 also includes processor(s) 256 and memory 258(computer-readable storage media 258, CRM 258). The processor(s) 256 maybe a single-core processor or a multiple-core processor composed of avariety of materials, such as silicon, polysilicon, high-K dielectric,copper, and so on. The computer-readable storage media described hereinexcludes propagating signals. CRM 258 may include any suitable memory orstorage device such as random-access memory (RAM), static RAM (SRAM),dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), orFlash memory useable to store device data 260 of the access point 120.The device data 260 includes applications, and/or an operating system ofthe access point 120 that are executable by processor(s) 256 to enablewireless communication with the electronic device(s) 110. In the contextof the disclosure, the CRM 258 is implemented as storage media, and thusdoes not include transitory signals or carrier waves.

CRM 258 also includes an access point manager 262 (access point managerapplication 262). Alternately or additionally, the access point manager262 may be implemented in whole or part as hardware logic or circuitryintegrated with or separate from other components of the access point120. In at least some aspects, the access point manager 262 configuresthe transceiver(s) 254 to implement the techniques described herein fora switching scheme for opting in and out of MU-OFDMA. The access pointmanager 262 also configures a network interface 264 to relaycommunications between the electronic device(s) 110, the access point120, and an external network.

Example Methods

Example methods 300, 400, and 500 are described with reference to FIGS.3-5 , respectively, in accordance with one or more aspects of aswitching scheme for opting in and out of MU-OFDMA. The order in whichthe method blocks of methods 300, 400, and 500 are described is notintended to be construed as a limitation, and any number of thedescribed method blocks can be skipped, repeated, or combined in anyorder to implement a method or an alternate method. Generally, any ofthe components, modules, methods, and operations described herein can beimplemented using software, firmware, hardware (e.g., fixed logiccircuitry), manual processing, or any combination thereof. Someoperations of the example methods may be described in the generalcontext of executable instructions stored on computer-readable storagememory that is local and/or remote to a computer processing system, andimplementations can include software applications, programs, functions,and the like. Alternatively or in addition, any of the functionalitydescribed herein can be performed, at least in part, by one or morehardware logic components, such as, and without limitation,Field-programmable Gate Arrays (FPGAs), Application-specific IntegratedCircuits (ASICs), Application-specific Standard Products (ASSPs),System-on-a-chip systems (SoCs), Complex Programmable Logic Devices(CPLDs), and the like.

FIG. 3 depicts an example method 300 for opting in and out of MU-OFDMAwhen uplink traffic is high. During periods of high uplink traffic, itmay be more efficient for the electronic device 110 to opt out ofMU-OFDMA rather than sharing the bandwidth of a transmit channel withother devices. At 302, an electronic device enters an MU-OFDMA mode forcommunicating with an access point via a wireless network over ashared-channel bandwidth. For example, an electronic device (e.g., theelectronic device 110) transmits an Operation Mode Indication (OMI) toan access point (e.g., the access point 120) to request initiation ofthe MU-OFDMA mode. The access point controls and synchronizes uplinktransmissions of multiple electronic devices in the MU-OFDMA mode toenable simultaneous multiple-user transmissions to occur.

At 304, the electronic device initiates a timer T1 (e.g., a first timerT1). The timer T1 may be any suitable timing mechanism and may be set toany suitable length of time, such as approximately 500 milliseconds(ms). The timer T1 is used to provide a minimum amount of time in whichthe electronic device 110 remains in the MU-OFDMA mode before switchingto a different mode, such as the single-user mode.

At 306, the electronic device 110 determines if an uplink (UL) queuesize is greater than a first threshold size TH-1 for the uplink queue.The uplink-queue size may provide an indication of high or low uplinktraffic. An example threshold size may include a threshold sizesubstantially equal to a size of a transmit channel, approximately twomegabytes (MB) of data, or any other suitable size. In oneimplementation, the electronic device 110 uses the first threshold sizeTH-1 to determine if the uplink data is sufficient to fill the entiretransmit channel. If the channel can be filled by the uplink data, thenno efficiency is lost by not sharing bandwidth of the transmit channelaccording to the multi-user mode.

If the uplink-queue size is not greater than the first threshold sizeTH-1 (e.g., “NO” at 306), then the electronic device 110 continues tomonitor the size of the uplink queue. If the uplink-queue size isgreater than the first threshold size TH-1 (“YES” at 306), then at 308the electronic device determines if the timer T1 is expired. If thetimer T1 is not yet expired (“NO” at 308), then the electronic device110 continues to monitor the uplink-queue size relative to the firstthreshold size TH-1 at 306. The timer T1 prevents the electronic device110 from opting out of the MU-OFDMA mode too quickly after entering theMU-OFDMA mode.

If the timer T1 is expired (“YES” at 308), then at 310 the electronicdevice 110 opts out of the MU-OFDMA mode. Opting out of the multi-usermode enables the electronic device 110 to not be limited to requirementsof the access point under the multi-user mode. In an example, theelectronic device 110 can send an OMI signal to the access point 120 toindicate that the electronic device is selecting to exit the MU-OFDMAmode and contend for the transmit channel in a single-user mode. Inparticular, the electronic device 110 can send a frame with an OMControl subfield having an uplink MU Disable subfield set to one (1), orhaving the uplink MU Disable subfield set to zero (0) and an uplink MUData Disable subfield set to one (1). The electronic device 110 canreceive an acknowledgment signal (e.g., ACK) from the access point 120indicating that the MU-OFDMA mode is disabled for the electronic device110. When this frame is acknowledged by the access point, the electronicdevice can ignore the MU-OFDMA EDCA parameter set, which is mandated bythe access point and may have relaxed values in comparison to standardEDCA parameters included in an initial EDCA parameter set informationelement used by the access point. The electronic device 110 may thenapply the standard EDCA parameters included in the initial EDCAparameter set information element, which do not have relaxed values.

At 312, the electronic device 110 enters the single user (SU) mode tocontend for the transmit channel. The single-user mode enables theelectronic device to contend for the transmit channel using differentparameters than the parameters mandated by the access point as part ofthe multi-user mode, enabling the electronic device 110 to contend forthe transmit channel as aggressively as a legacy device and/or theaccess point 120.

At 314, the electronic device 110 initiates a timer T2 (e.g., a secondtimer 72) in response to entering the single-user mode. The timer 72 maybe set for any suitable duration of time, such as approximately 500 ms.The timer 72 may prevent the electronic device 110 from exiting thesingle-user mode too quickly, essentially ping-ponging back and forthbetween the multi-user mode and the single-user mode. Accordingly, thetimer T2 provides a minimum amount of time for the electronic device 110to operate in the single-user mode before it can attempt to re-enter themulti-user mode.

At 316, the electronic device 110 determines if the uplink-queue size isbelow a second threshold size TH-2. An example of the second thresholdsize TH-2 may include a threshold size substantially equal to half thesize of a transmit channel, approximately one MB of data, or any othersuitable size. The first threshold size TH-1 and the second thresholdsize TH-2 may be based on an access category (e.g., voice, video, besteffort, and background access categories) of the uplink data, such thateach threshold may differ for different access categories. For example,the first and second threshold sizes TH-1 and TH-2 can differ based onwhether the uplink data is for Voice-over-Internet Protocol (VoIP),online gaming, audio data, video data, etc. In addition, in each accesscategory, the first and second threshold sizes TH-1 and TH-2 can differ.An example implementation includes, for the voice access category, thefirst threshold size TH-1 set to one kilobyte (KB) and the secondthreshold size TH-2 set to 0.2 KB. In another implementation, for thevideo access category, the first threshold size TH-1 may be set to 10 KBand the second threshold size TH-2 may be set to 2 KB. An exampleimplementation for the best effort and background access categories mayinclude the first threshold size TH-1 set to 2 MB and the secondthreshold size TH-2 set to 1 MB. In another example, the first andsecond thresholds TH-1 and TH-2 may be dependent on the maximum latencyin an uplink queue, such that each threshold may differ for differentmaximum latencies in uplink queues. Although several examples aredescribed herein, any suitable threshold size may be used for the firstand second threshold sizes TH-1 and TH-2, and the sizes may depend onthe implementation. These examples are not intended to be limiting.

If the uplink-queue size is equal to, or greater than, the secondthreshold size TH-2 (“NO” at 316), then the electronic device 110remains in the single-user mode for transmitting uplink data. However,if the uplink-queue size drops below the second threshold size TH-2,then it is likely that the uplink traffic is sufficiently low to allowthe multi-user mode to be more efficient for the electronic device 110than the single-user mode. Accordingly, if the electronic device 110determines that the uplink-queue size has decreased to a size that isless than the second threshold size TH-2 (“YES” at 316), then at 318,the electronic device 110 determines if the timer 12 is expired, whichindicates that a sufficient amount of time has passed since entering thesingle-user mode. Alternatively, the electronic device 110 can waituntil the timer 72 expires before determining whether the uplink-queuesize is equal to, or greater than, the second threshold size TH-2.

If the timer T2 is not expired (“NO” at 318), then the electronic device110 remains in the single-user mode for transmitting uplink data.Accordingly, the electronic device 110 delays opting back in to theMU-OFDMA mode until expiration of the timer T2. If the timer T2 isexpired (“YES” at 318), then it is determined that the electronic device110 has spent a sufficient amount of time in the single-user mode, andthe electronic device 110 may proceed to opt in to the multi-user mode.

Other forms of hysteresis can be implemented between the two thresholdsizes TH-1 and TH-2 to reduce or prevent ping-ponging between themulti-user and single-user modes. For example, instead of using thetimer T2 (or in addition to using the timer T2), the electronic device110 can wait for the uplink-queue size to fall below the secondthreshold size TH-2 by a predefined amount (e.g., value or percentage)before determining whether to opt in to the multi-user mode. A thirdthreshold size can be used that is less than the second threshold sizeTH-2 by the predefined amount. This additional condition may furtherreduce the likelihood of the electronic device 110 bouncing back andforth between single-user and multi-user modes.

At 320, the electronic device 110 opts in to the MU-OFDMA mode. This canbe achieved by the electronic device 110 transmitting an OMI signal, tothe access point 120, requesting to participate in the multi-user mode.The electronic device 110 receives an acknowledgment signal, from theaccess point 120, providing permission and information to enter themulti-user mode. The electronic device 110 can then re-enter theMU-OFDMA mode at 302.

FIG. 4 illustrates an example method 400 for opting out of MU-OFDMA tohonor low-latency Quality-of-Service (QoS) requirements. The method 400may be performed by the electronic device 110 when implementing alow-latency application that requires quick access to uplink anddownlink channels. At 402, an electronic device (e.g., the electronicdevice 110) connects to a wireless network using an MU-OFDMA mode.

At 404, the electronic device 110 enters a low-latency mode for uplinktraffic. The electronic device 110 may enter the low-latency mode whenperforming functions or executing an application having data load orlatency requirements that are critical, such as online gaming.

At 406, the electronic device 110 receives a plurality of triggers froman access point (e.g., the access point 120). Triggers (e.g., triggerframes) are used by the access point 120 to schedule multi-usertransmissions in both uplink and downlink directions. The access point120 acts as a central coordinating entity and assigns time-frequencyresource units (RUs) for reception or transmission to associatedstations, which avoids RU contention overhead and increases efficiencyin scenarios of dense deployments. For example, the access point 120(Wifi AP) sends a downlink trigger frame to inform particular stationsto send their data. The trigger frame includes information identifying atransmission interval, a bit rate of transmission, and a transmit powerfor the station (the electronic device(s) 110) to use for the uplinktransmission. The information in the trigger is defined in the 802.11axspecification.

At 408, the electronic device 110 monitors a frequency at which thetriggers are received from the access point 120. In particular, theelectronic device 110 monitors an average inter-arrival time of thetriggers received from the access point 120.

At 410, the electronic device 110 determines if the frequency is greaterthan a threshold frequency TH-f. Any suitable threshold frequency TH-fcan be used as a measure for an acceptable frequency for the triggers.In some aspects, the threshold frequency TH-f can be based on a type ofapplication being used (e.g., VoIP application, online gamingapplication, etc.), a type of data (e.g., voice traffic, video data,audio data, etc.), or a particular access category of the uplink data.If the frequency is greater than the threshold frequency TH-f (“YES” at410), then the electronic device 110 maintains the MU-OFDMA mode andcontinues to monitor the frequency at 408. The threshold frequency TH-fmay represent a maximum queuing delay. When the frequency of thetriggers is greater than the threshold frequency TH-f, then the triggersare being sent by the access point 120 fast enough to retain highefficiency in the multi-user mode.

If the frequency is less than the threshold frequency TH-f (“NO” at410), then at 412, the electronic device 110 opts out of the MU-OFDMAmode. When the frequency of the triggers drops below the thresholdfrequency TH-f, the electronic device 110 can determine that, for somereason, the access point 120 is not responsive enough for thelow-latency requirements. Delayed triggers result in more transmissiondelay. Accordingly, to improve efficiency, the electronic device 110 canselect to opt out of the MU-OFDMA mode.

At 414, the electronic device 110 enters a single-user mode to contendfor a transmit channel on the wireless network without restrictionsmandated by the access point. As above, the single-user mode (afteropting out of the multi-user mode) enables the electronic device 110 toavoid scheduling and shared-channel bandwidth requirements set by theaccess point for the multi-user mode. Further, by opting out of themulti-user mode and switching to the single-user mode, the electronicdevice 110 avoids being penalized on latency, which would occur if theelectronic device 110 did not opt out of the multi-user mode and simplyused a relaxed set of contention parameters provided by the access point120.

In some scenarios, after entering the low-latency mode at 404, theelectronic device 110 may, at 416, receive no triggers from the accesspoint over a predefined duration of time, or may receive only a singletrigger over the duration of time. In such scenarios, the method 400proceeds directly from 416 to 412 to opt out of the MU-OFDMA mode.

As latency requirements are relaxed, or after a predefined period oftime, the electronic device 110 can optionally, at 418, opt back in tothe MU-OFDMA mode. Then the method 400 may proceed to receiving triggers(at 406), or not receiving triggers (at 416), and monitoring (at 408)the frequency at which the triggers are received from the access point120.

FIG. 5 illustrates an example method 500 for opting out of MU-OFDMAbased on Basic Service Set (BSS) metrics. At 502, when connected to awireless network using an MU-OFDMA mode, the electronic device 110indicates to an access point of the wireless network uplink data totransmit.

At 504, the electronic device 110 receives one or more triggers from theaccess point for transmitting the uplink data. In an example, thetriggers include a mandated modulation and coding scheme (MCS) providedby the access point.

At 506, the electronic device 110 performs a BSS clear channelassessment (CCA) of a transmit channel. A BSS CCA Busy is a Wi-Fi metricindicating how busy or clear the air time of a channel is. Theelectronic device 110 can monitor the channel busy time over a durationof time to obtain this metric. For example, the electronic device 110listens for radio frequency (RF) transmissions at a physical layer of anair interface. The electronic device 110 uses a signal-detect thresholdto identify a preamble transmission from another transmitting radio(e.g., the access point 120) for synchronization between devices. Inaddition, the electronic device 110 uses an energy-detect threshold todetect other types of RF transmissions during the CCA.

At 508, the electronic device 110 measures a received signal strengthindicator (RSSI) of the transmit channel if the transmit channel isclear. This measurement provides an indication as to the quality of thesignal on the transmit channel, which is in turn an indication of howfast the electronic device 110 can transmit data.

At 510, the electronic device 110 estimates an MCS based on the measuredRSSI. The estimated MCS indicates how many bits the electronic device110 can transmit per symbol on the transmit channel.

At 512, the electronic device 110 determines if a data rate associatedthe estimated MCS is greater than a data rate associated with themandated MCS. In some aspects, the electronic device 110 can determineif the data rate associated with the estimated MCS is greater than thedata rate associated with the mandated MCS by a threshold amount 7′. TheMCS is an index to an array of rates, such that a higher MCS correspondsto a higher rate, and a lower MCS corresponds to a lower rate.

If the data rate associated with the estimated MCS is less than the datarate associated with the mandated MCS (“NO” at 512), then at 514, theelectronic device 110 remains in the MU-OFDMA mode and transmits theuplink data using the MU-OFDMA mode according to the mandated MCS. Insome aspects, the method 500 may proceed to 514 if the electronic device110 determines that the data rate associated with the estimated MCS isgreater than the data rate associated with the mandated MCS, but thedifference between the data rates is less than the threshold amount T.

If the data rate associated with the estimated MCS is greater than thedata rate associated with the mandated MCS (“YES” at 512), then at 516,the electronic device 110 opts out of the MU-OFDMA mode. Alternatively,the electronic device 110 opts out of the MU-OFDMA mode at 516 if thedata rate associated with the estimated MCS is greater than the datarate associated with the mandated MCS by at least the threshold amountT.

At 518, the electronic device 110 enters a single-user mode to contendfor the transmit channel on the wireless network for transmission of theuplink data without restrictions mandated by the access point 120.

CONCLUSION

Although aspects of a switching scheme for opting in and out of MU-OFDMAhave been described in language specific to features and/or methods, thesubject of the appended claims is not necessarily limited to thespecific features or methods described. Rather, the specific featuresand methods are disclosed as example implementations of the switchingscheme for opting in and out of MU-OFDMA, and other equivalent featuresand methods are intended to be within the scope of the appended claims.Further, various different aspects are described, and it is to beappreciated that each described aspect can be implemented independentlyor in connection with one or more other described aspects.

1.-15. (canceled)
 16. A method performed by an electronic device, themethod comprising: when connected to a wireless network using amulti-user orthogonal frequency multiple access (MU-OFDMA) mode,indicating to an access point of the wireless network that theelectronic device has uplink data to transmit; receiving one or moretriggers from the access point for transmitting the uplink data, the oneor more triggers including a mandated modulation and coding scheme(MCS); measuring a signal strength of a transmit channel; estimating anMCS based on the measured signal strength; and comparing a first datarate associated with the estimated MCS to a second data rate associatedwith the mandated MCS to determine whether to opt out of the MU-OFDMAmode.
 17. The method of claim 16, further comprising: opting out of theMU-OFDMA mode based on the first data rate associated with the estimatedMCS being greater than the second data rate associated with the mandatedMCS; and entering a single-user mode to contend for the transmit channelfor transmitting the uplink data without access restrictions mandated bythe access point in the mandated MCS.
 18. The method of claim 17,wherein the opting out is based on the first data rate associated withthe estimated MCS being greater than the second data rate associatedwith the mandated MCS by a threshold amount.
 19. The method of claim 17,wherein the opting out includes transmitting an operation modeindication (OMI) to the access point to indicate that the electronicdevice selects to not participate in the MU-OFDMA mode with the accesspoint.
 20. The method of claim 16, further comprising: determining thatthe first data rate associated with the estimated MCS is greater thanthe second data rate associated with the mandated MCS; determining thata difference between the first data rate associated with the estimatedMCS and the second data rate associated with the mandated MCS is lessthan a threshold amount; and responsive to the difference being lessthan the threshold amount, transmitting the uplink data according to theMU-OFDMA mode and the mandated MCS.
 21. The method of claim 16, furthercomprising: performing a clear channel assessment (CCA) of the transmitchannel.
 22. The method of claim 21, wherein performing the CCA of thetransmit channel comprises at least one of: utilizing a signal-detectthreshold to identify a preamble transmission from another transmittingradio for synchronization between devices during the CCA; or utilizingan energy-detect threshold to detect radio frequency transmissionsduring the CCA.
 23. An electronic device comprising: a memory andprocessor system configured to execute instructions stored in the memoryto implement an access-mode manager application configured to: whenconnected to a wireless network using a multi-user orthogonal frequencymultiple access (MU-OFDMA) mode, indicate to an access point of thewireless network that the electronic device has uplink data to transmit;receive one or more triggers from the access point for transmitting theuplink data, the one or more triggers including a mandated modulationand coding scheme (MCS); measure a signal strength of a transmitchannel; estimate an MCS based on the measured signal strength; andcompare a first data rate associated with the estimated MCS to a seconddata rate associated with the mandated MCS to determine whether to optout of the MU-OFDMA mode.
 24. The electronic device of claim 23, whereinthe access-mode manager application is further configured to: opt out ofthe MU-OFDMA mode based on the first data rate associated with theestimated MCS being greater than the second data rate associated withthe mandated MCS; and enter a single-user mode to contend for thetransmit channel for transmitting the uplink data without accessrestrictions mandated by the access point in the mandated MCS.
 25. Theelectronic device of claim 24, wherein the access-mode managerapplication is configured to opt out based on the first data rateassociated with the estimated MCS being greater than the second datarate associated with the mandated MCS by a threshold amount.
 26. Theelectronic device of claim 24, wherein the access-mode managerapplication is configured to opt out by transmitting an operation modeindication (OMI) to the access point to indicate that the electronicdevice selects to not participate in the MU-OFDMA mode with the accesspoint.
 27. The electronic device of claim 23, wherein the access-modemanager application is further configured to: determine that the firstdata rate associated with the estimated MCS is greater than the seconddata rate associated with the mandated MCS; determine that a differencebetween the first data rate associated with the estimated MCS and thesecond data rate associated with the mandated MCS is less than athreshold amount; and responsive to the difference being less than thethreshold amount, transmit the uplink data according to the MU-OFDMAmode and the mandated MCS.
 28. The electronic device of claim 23,wherein the access-mode manager application is further configured to:perform a clear channel assessment (CCA) of the transmit channel. 29.The electronic device of claim 28, wherein the access-mode managerapplication is configured to perform the CCA of the transmit channel byat least one of: utilizing a signal-detect threshold to identify apreamble transmission from another transmitting radio forsynchronization between devices during the CCA; or utilizing anenergy-detect threshold to detect radio frequency transmissions duringthe CCA.
 30. A non-transitory computer readable medium embodying a setof executable instructions, the set of executable instructions tomanipulate at least one processor of an electronic device to: whenconnected to a wireless network using a multi-user orthogonal frequencymultiple access (MU-OFDMA) mode, indicate to an access point of thewireless network that the electronic device has uplink data to transmit;receive one or more triggers from the access point for transmitting theuplink data, the one or more triggers including a mandated modulationand coding scheme (MCS); measure a signal strength of a transmitchannel; estimate an MCS based on the measured signal strength; andcompare a first data rate associated with the estimated MCS to a seconddata rate associated with the mandated MCS to determine whether to optout of the MU-OFDMA mode.
 31. The non-transitory computer readablemedium of claim 30, wherein the set of executable instructions furthermanipulate the at least one processor to: opt out of the MU-OFDMA modebased on the first data rate associated with the estimated MCS beinggreater than the second data rate associated with the mandated MCS; andenter a single-user mode to contend for the transmit channel fortransmitting the uplink data without access restrictions mandated by theaccess point in the mandated MCS.
 32. The non-transitory computerreadable medium of claim 31, wherein the at least one processor isconfigured to opt out based on the first data rate associated with theestimated MCS being greater than the second data rate associated withthe mandated MCS by a threshold amount.
 33. The non-transitory computerreadable medium of claim 31, wherein the at least one processor isconfigured to opt out by transmitting an operation mode indication (OMI)to the access point to indicate that the electronic device selects tonot participate in the MU-OFDMA mode with the access point.
 34. Thenon-transitory computer readable medium of claim 30, wherein the set ofexecutable instructions further manipulate the at least one processorto: determine that the first data rate associated with the estimated MCSis greater than the second data rate associated with the mandated MCS;determine that a difference between the first data rate associated withthe estimated MCS and the second data rate associated with the mandatedMCS is less than a threshold amount; and responsive to the differencebeing less than the threshold amount, transmit the uplink data accordingto the MU-OFDMA mode and the mandated MCS.
 35. The non-transitorycomputer readable medium of claim 30, wherein the set of executableinstructions further manipulate the at least one processor to: perform aclear channel assessment (CCA) of the transmit channel.